How do I generate all possible torrent info hashes? I am looking for an elegant way to do so.
python code would be immensely appreciated, any other langues are cool too.
Start with a hash of all 0
Increment by 1.
Go to step 2.
This will obviously run for quite awhile, but will generate all possible torrent info hashes.
Related
According to this comment from the general question Is it possible to create a quine in every turing-complete language? it seems like it is said that it's possible.
However I didn't find any Ook! Quine on the internet.
Do you think that it's really possible?
And if yes will we be able to find it?
It wouldn't even be very difficult. You would want to code it in brainfuck and then translate, and the internal representation for each command should be a pair of numbers (probably from 0-2) to represent the punctuation of each half-command. You could borrow much of the structure from Erik Bosman's brainfuck quine.
Updated: here. https://gist.github.com/danielcristofani/1fe53487df1f7afcb5b91c06d95184b2
This is ~40 commands taken directly from Erik Bosman's quine, another ~120 freshly written commands of rather clunky output code to handle Ook!'s verbosity, and then the data segment to represent all that.
I have a bunch of scripts that I wrote at times when I did not realize how use v1.2.3; can be useful. So some of them may be using features from later versions of perl, some of them may be OK with, say, perl 5.8.
Now I would like to get that into some order and add proper uses where there is need for them, just to be able to sleep better. :-)
How should I do that? Is there any tool that could help me make an educated guess?
Perl::MinimumVersion
Find a minimum required version of perl for Perl code
The most reliable way is 1) to write a decent test suite, then 2) to run your tests using each version of Perl.
You've surely already done the first part (!), and the second part is actually pretty easy to do using perlbrew.
I am working on writing a SHA512 function. When i check the file I am encrypting on different sources, a Linux SHA512SUM tool, a couple websites, and run it through the old source code i have for SHA512, they all give different hash values. My thought going into this project is that all Hash algorithms will output the same hash value if implemented correctly, to be used as a check sum. Am I wrong in thinking this? If I am wrong how would I really check to see if my work is correct?
Thanks in advance.
Yes, that's one of the basic building block of PKI: the same data block passed to a hash should always return the same hash value.
beware of the interpretation, though: the result of a SHA-2(512) hash is a block of 512 bits, not a string value so it will first be encoded for human consumption and it is therefore possible that you see what looks like visually different results when it's simply a matter of using different encodings.
I'm looking for some tool/library that would scan given project tree, and report on code duplicates - i.e. blocks of code that are repeated in various files.
Is there anything like this?
As it is now, I have to view them (files) all, and search for duplicates, but it doesn't strike me as very efficient.
A System for Detecting Software Plagiarism might work; it supports Perl.
And here's a list.
I'm looking for a special hash-function. Let's say I have a large list of strings, if I order them by their hash-values they should be ordered quasi randomly.
The most important point is: it must be super fast. I've tried md5 and sha1 and they're using to much cpu power.
Clashes are not a problem.
I'm using javascript, so it shouldn't be too complicated to implement.
Take a look at Murmur hash. It has a nice space/collision trade-off:
http://sites.google.com/site/murmurhash/
It looks as if you want the sort of hash function used in a hash table, not the sort used to detect duplicates or tampering.
Googling will yield you a wealth of information on alternative hash functions. To start with, stay away from cryptographic signature hashes (like MD-5 or SHA-1), they solve another problem.
You can read this, or this, or this, to start with.
If speed is paramount, you can implement a simple ad-hoc hash, e.g. take the first and last letter and order your string by the last and then first letter. The result would look, as you say, "quasi random" and it would be fast. For instance, part of my answer sorted that way would look like this:
ca ad-hoc
el like
es simple
gt taking
hh hash
nc can
ti implement
uy you
Hsieh, Murmur, Bob Jenkin's comes to my mind.
A nice page about hash functions that has some tests for quality and a simple S-box hash as well.